Telephone-exchange system



H. P. CLAUSEN.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED IUNEYZS, I917.

1,3453348. t t d uly 6, 1920.

/n ven for: Henry F C/ausen UNITED STATES PATENT OFFICE.

HENRY I. GLAUSEN, OF MOUNT VERNON, NEW YORK, ASSIGNOR TO WESTERNELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORA- TION OFNEW YORK.

Specification 0! Letters Patent.

TELEPHONE-EXCHANGE SYSTEM;

' Patented July 6, 1920.

Application filed .Tune 25, 1917. Serial No. 176,808.

trunk circuits between originating (A) or terminating (B) boards forinterconnecting telephone lines terminating at the different boards,which may be in the same or different central offices.

In such systems it is frequently desirable that the connection to thewanted line including the trunk circuit and a link circuit be built upand that the application of ringing current to the wanted line bedelayed until such time as the operator at the A board determines. Thisis particularly desirable in working connections between local and tolllines, when it is economical to hold the local line while building upthe connection between the link circuit and an expensive toll line. Insystems of this character, it is usual for the operator at the A boardto have complete charge of the supervision over such connections, so theconnection to the wanted local line may be built and held awaiting thebuilding up of the connection with the more expensive toll line, atwhich time the operator may cause the wanted local line to be signaled.It is the object of this invention to provide a system for accomplishingthe desirable results above set forth. p

In accordance with this invention, a trunk circuit extending between anA and a B board may be connected at its incoming end with a telephoneline, and a link circuit may be connected with the outgoing end thereofwithout applying ringing current to the telephone line until such timeas the operator at the A board determines. There is associated with thetrunk circuit apparatus, by means of which, when the operator at thecentral ofiiceX causes the momentary actuation of a switch, ringingcurrent is connected with the wanted telephone line and is thenautomatically disconnected therefrom upon the response of the calledsubscriber.

For a complete understanding of this inventlon, reference should be hadto the fol-. lowing description considered in connection with theaccompanying drawing showing a telephone exchange system containing oneembodiment of this invention. In the drawing, there is shown a telephoneline A which a may. be connected in any desired manner with a cordcircuit 0, located at a central oflice X, and another telephone line Bterminating at a central office Y, at which is located the incoming endof a trunk circuit D, the outgoing end of which is located at thecentral oflice X. For convenience, the

operator at central oflice X will be hereinafter designated as the Aoperator, and the operator at central ofiice Y as the B operator.

Assuming that it is desired to build up a connection with and hold lineB while the connection with'line A is being built up and to delay theapplication of ringing current to line B until the connection with lineA has been built up, the Afoperator communicates with the B operatorover an I order wire circuit (not shown) and receives a trunkassignment, after which the A operator inserts plug 5 of the cordcircuit G into the jack 6 of the trunk circuit D and the B operatorinserts plug 15 of trunk circuit D into jack 16 of-line B. The insertionof the plug 5 into the jack 6 causes I the lighting of supervisory lamp36 and the operation of relay 7. Supervisory relay 8 does not operatewhen in-series with the high resistance left-hand winding of relay 7,but does operate when the low resistance righthand'winding thereof isincluded in the circuit in parallel with the left-hand winding, as willmore fully hereinafter appear. If the B operator has not inserted theplug 15 into the jack 16 the operation of relay 7 causes the lighting oflamp 9 over a circuit from battery through the lamp 9 contact-of relay7, lower normal contact of relay 10 and resistance 11 to ground, but ifthe plug 15 has been inserted into jack 16, the lamp 9 will'not belighted by the operation of rerelay 10 and cut-ofi' relay 17. Relay 10,in

operating, closes its contacts 18 and 19 before contact 20 thereof isclosed, so that fast operating relay 21 operates before the'slow-to-operate relay 22 can attract. its armatures. The operatingcircuit for relay 21 may be traced from battery through the normalcontact of relay 22, winding of relay 21, contact 18 of relay 10,contact of relay 7, winding of relaylO, sleeve contacts of the plug 15and the jack 16 and the winding of cut-off relay 17 to ground,'relay21,1in' operating, ,completesa locking circuit for itself, whichincludes its alternate contact. The winding of relay 21 is now connectedin parallel with the lamp 9, forming a shunt. about and e'lfacingthis'lampp Upon the closure of contact 20 of relay 10, followingthe'lclosure of contact '18, slow-operating relay 22 is actuated over acircuit from battery through the w nd ng of relay 22, contacts 20 and18, contact of relay 7, winding of relay 10, sleeve contacts of the plug15 andthe jack 16 and the winding of cut-off relay 17to ground. Relay22, in operating, opens its normal contact in the initial energizingcircuit of relay 21, and closes, at its right-hand alternate contact, ashort circuit for and prevents the operation of the ringing relay 25.This short circuit also includes the alternate contact of relay 21.-

When the building up of the connection with line A is accomplished the Aoperator is suitably advised, and momentarily 'actuates a' key 27,causing the momentary openin of the circuit of relay '7, which re leasesits armature and then attracts the armature againupon the closure of thecircuit. The release of the armature of relay 7 opens the circuit ofrelay 21, which releases its armature, opening the short circuit ofringing relay 25. Relay 22 is made slow in releasing so that it'does notrelease its armatures while the contact of relay 7 is open for the shorttime. Upon the closure of the contact of relay 7 following therestoration of key 27 to normal position, ringing relay 25 immediatelyoperates over a circuit from battery through the winding of ringingrelay 25, right-hand alternate contact of relay 22, normal contact'ofrelay 21, contact of tripping relay 30, left-hand alternate-contact ofrelay 22, contact 18,

contact of relay 7, winding of relay 10, sleeve contacts of the plug 15and the jack 16 and. the winding of cut-off relay 17 to ground. Theoperation of ringing relay 25 connects a source of ringing current 31,through the winding of tripping relay 30, to line B, thereby to causethe actuation of call bell 32 at the station of. line B. In respond- Jing to' the operation of the call bell, subscriber B removes thereceiver from the switchhook, whereupon tripping relay "30 operates,opening its contact, thereby remov mg a short circu t from. the windingof reing.

1 ing supervis lay 21. Relay 21 thereupon operates and locks up,establishing a short circuit for ringing relay '25, which then releasesits armatures to disconnect ringing current from the line and tocomplete the talking circuit. Immediately upon the completion of thetalking circuit, supervisory relay 33 is operated, therebycompleting acircuit, through V the right-hand winding of relay 7, to connect it inparallel with the left-hand wind- The resistance in circuit with super-1 visory relay 8 is thereby'decreased, permitting this relay to operateand establish a shunt circuit including resistance 28 for call ory lamp36, whereby the lamp is effaced;

At the conclusion of the conversation, the

subscribers restore their respective receivers to the switchhooks. Therestoration of'the receiver to the switchhook by subscriber B causes thedeenergization of supervisory relay 33, which, in releasing itsarmature, opens the circuit of and removes the righthand winding ofrelay 7 from the circuit which includes the winding of supervisory relay8, thereby causing the release of supervisory-relay 8. Upon the releaseof this supervisory relay, calling supervisory lamp 36 is lighted tofurnish the A operator a disconnect signal. The A operator may nowwithdraw the plug 5 from the jack 6,

restoring the apparatus of the cord circuit- If desired, the momentaryrelease of the trunk relay 7 may be accomplished by the VVIDOIIIQIIULI'Ywithdrawal of the plug 5 from the jack 6. The key 27 may then beomitted.

v What is claimed is: V

1. A telephone exchange system comprise ing a trunk circuit extendingfrom a first to a second switchboard, a link circuit at the firstswitchboard connected with the trunk circuit, a source of ringingcurrent, a telephone line, apparatus responsive to the connection of thetrunk circuit with the telephone line for preventing the connection ofthe source of ringing current to the telephone line, a switch at thefirst switchboard,

means responsive to the actuation of the switch to connect the source ofringing'currentto the line, and a relay energized upon the closure ofthe telephone/line to disconnect the ringing current therefrom. I I

' 2. A telephone exchange circuit comprising' a trunk circuit extendingfrom a first to a second cwitchboard, a link circuit at the firstswitchboard CQIlnected-with the trunk Cir ' phone line for preventingthe connection of the source of ringing current to the telephone line, aswitch at the first switchboard,

switching mechanism responsive to the actuation of the switch to connectthe source of ringing current to the telephone line, and anelectromagnetic switch responsive to the closure of the telephone linefor causing the disconnection of the source of ringing currenttherefrom.

3. A telephone exchange system comprising a trunk circuit extending froma first to a second switchboard, a link circuit adapted to be connectedwith the trunk circuit, a source of ringing current, a telephone lineterminating at the second switchboard, a ringing relay associated withthe trunk circuit for connecting the source of ringing current to theline and maintaining such connection until the subscriber answers, anenergizing circuit for the ringing relay, means operated upon theconnection of the link circuit with the trunk circuit for pregventmg theestablishment of said energlz ing circuit, and a switch at the firstswitchboard adapted when actuated to cause the release of said meansthereby causing the energization of said ringing relay for connectingthe source of ringing current with the line.

4. A telephone exchange system comprising a trunk circuit extending froma first to a second switchboard, a link circuit at the first switchboardadapted to be connected with the trunk circuit, a telephone lineterminating at the second switchboard, a signaling device, a relay inthe trunk circuit energized upon the connection of the link circuit withthe trunk circuit to cause the operation of the signaling device,

a source of ringing current, a ringing relay.

associated with the trunk circuit for connecting the source of ringingcurrent to the line and maintaining such connection until the subscriberanswers, means responsive to the energization of the trunk relay, adisabling circuit for the ringing relay established upon the operationof such means, and a switch at the first switchboard, said trunk relaybeing deenergized upon the momentary actuation of the switch to causethe release of said means thereby opening the disabling circuit of theringing relay and causing the operation thereof to connect the source ofringing current to the telephone line.

5. A telephone exchange system comprising a trunk circuit extending froma first to a second switchboard, a link circuit at the first switchboardconnected with the trunk circuit, a telephone line terminating at thesecond switchboard, a source of ringing ourrent, a ringing relay forconnecting the source of ringing current to the telephone line, a fastand a slow-operating relay energized upon the connection of the trunkcircuit with the telephone line to prevent the operation of the ringingrelay, a locking circuit for the fast-operating relay completed upon theenergization thereof, a switch at the first switchboard, and aswitching'device responsive to the actuation of the switch for openingthe locking circuit and thereafter cooperating with the fast-operatingrelay to cause the operation of the ringing relay.

6. A telephone exchange system comprising a trunk circuit extending froma first to a second switchboard, a link circuit at the firstswitchboard, a trunk relay in the trunk circuit energized upon theconnection of the link circuit therewith, a telephone line terminatingat the second switchboard, a source of ringing current, a ringingrelayadapted when energized to connect the source of ringing current tothe telephone line, a fast and a slow-operating relay energized upon theconnection of the trunk circuit with 'the telephone line to prevent theenergization of the ringing relay, a locking circuit for thefast-operating relay completed'upon the energization thereof andincluding a contact of the trunk relay, a switch at the firstswitchboard controlling the trunk relay, and an energizing circuit forthe ringing relay completed upon the denergization of the fast-operatingrelay followed by the energization of the trunk relay.

7 A telephone exchange system comprising a trunk circuit extending froma first to a second switchboard, a link circuit at the firstswitchboard, a trunk relay in the trunk circuit energized upon theconnection of the link circuit therewith, a telephone line terminatingat the second switchboard, a source of ringing current, a ringing relayadapted when energized to connect the source of ringing current to thetelephone line, a fast and a slow-operating relay energized upon theconnection of the trunk circuit with the telephone line to prevent theenergization of the ringing relay, a locking circuit for thefast-operating relay completed upon the energization thereof andincluding a contact of the trunk relay, a switch at the firstswitchboard controlling the trunk relay, an energizing circuit for theringing relay completed upon the deenergization of the fastoperatingrelay followed by the energization of the trunk relay, and a trippingrelay responsive to the closure of the telephone line and cooperatingwith the fast-operating relay to cause the deenergization of the ringingrelay.

8. A telephone exchan e system comprising a trunk circuit exten ing froma first to a second switchboard, a link circuit at the firstswitchboardconnected with the trunk circuit,-a telephone line terminating at the 7second switchboard, a source of ringing current, a ringing relay adaptedwhen operated to connect the source of ringing current to,

the telephone line, a local relay responsive to the connection of thetrunk circuit with the switchboard, and a switching device re-' 7 rentwith the telephone line, a fast and a telephone line, a disablingcircuit for the ringing relay established upon the energization ofthelocal relay, a switch at the first sponsive to the actuation of theswitch for rendering the disabling circuit inefi'ective therebypermitting the operation of the ringing relay.

9. Atelephone exchange system comprising a trunk circuit extending froma first to a second switchboard, a link circuit at the first switchboardconnected with the trunk" circuit, a telephone line terminating at thesecond switchboard, a source of ringing current, a ringing relay adaptedwhen energizedto connect the source of ringing curslow-operating'relayenergized upon the v connection of the trunk circuit with the telephoneline, a disabling circuit for the ringing relay established upontheenergization of the fast and slow-operating relays and including acontact of the fast-operating relay, a switch at the firstswitchboard,'and a switching device responsive to the actuation of theswitch for rendering the. disabling circuit ineffective therebypermitting the energization of theringing relay to connect the source ofr nging current to the line.

a second switchboard, a link circuit at the first switchboard adapted tobe connected with the trunk circuit, a telephone line ter minating atthe secondswitchboard,a switch at the first switchboard, a sourceofringing current, a ringing relay associated with 10. A telephoneexchange system compris- 111g a trunk circuit extending from a first tothe trunk circuit for connecting the source I of ringing current to theline, and means responsive to the connection of the link circuit withthetrunk circuitto establish a d sabling circuit for the ringing relay,said

